Manufacture of nitrostarch explosives



UNITED STATES PATENT OFFICE.

JESSE B. BRONSTEIN, OF ALLENTOWN, PENNSYLVANIA, ASSIGNOR TO TROJAN POWDER COMPANY, OF NEW YORK, N. 'Y., A CORPORATION OF NEW YORK.

MANUFACTURE OF NITROSTARCH EXPLOSIVES.

No Drawing.

To all whom it may concern:

Be it known that I, Jnssn B. BRONSTEIN, a citizen of the United States, and resident of Allentown, Lehigh county, Pennsylvania, have invented certain Improvements in the Manufacture of Nitrostarch Explosives, of which the following is a specification.

My invention relates to nitro-starch explosives, and its object is the production of such explosives with greatly increased strength and brisance as compared with nitro-starch explosives heretofore known A further object is to give to explosives of this class a somewhat plastic consistency.

Nitro-starch explosives as now manufactured, consisting essentially of nitro-starch and inorganic nitrates such as sodium and ammonium nitrates, are pulverulent in nature, having the consistency of ordinary flour or meal. The rate of detonation of pure nitro-starch is approximately 5200 meters per second, and that of ordinary nitrostarch explosives varies from about 2000 meters per second for mixtures containlng 20% nitro-starch, to 5000 meters per second for mixtures containing 80% nitro-starch. By reason of the pulverulent nature of the ingredients and the consequent free movement of the minute loose grains of nitrostarch during the progress of the detonating wave, it is preferable that each particle tends to move slightly from the compression forming the front of the detonating wave, so that each particle detonates only when it has reached the limit of the motion thus permitted. Furthermore in the pulverulent form of the explosive mixture voids are necessarily present, so that each nitro-starch particle is surrounded by a film of air which prevents the instantaneous rise in temperature necessary to insure the rapid continuance of the detonating wave. While these air films are very minute, they have a large influence as a retarder of the detonating wave.

Previous attempts have been made to increa'se the brisance of nitro-starch explosives, but not with substantial success. For exa p e, effort has been made to secure the Specification of Letters Patent.

Patented Nov. 29,1921.

Application filed September 24, 1919. Serial No. 325,927.

desired result by compression of the explos1ve and by the use of high pressure on the order of many thousands of pounds per square inch, nitro-starch explosives have been made substantially solid in nature and wlth a rate of detonation somewhat higher than the figures above given. The resulting explosives, however, were rigid bodies poorly adapted for commercial use in blasting, and furthermore while they appeared to be very dense and to have the nitro-starch particles in contact, as a matter of fact films of air still existed between said particles and reduced the rate of detonation much below that which I desire to obtain.

I have discovered that the rate of detonation of nitro-starch explosives can be increased very greatly by so modifying the physical consistency of the explosive mixture as to prevent the nitro-starch from having free movement under the influence of the detonating wave. This I accomplish by causing the nitro-starch particles to be held elastically in a viscous ground-mass forming a continuous medium of incompressible nature between and around said particles.

In selecting a viscous binding agent for the purpose stated, a number of factors must be taken into consideration. The material must not only possess the desired viscous and adhesive nature, but it must have no colloiding action upon the nitro-starch, and it must have no undue desensitizing effect upon the explosive. I am aware that explosives have hitherto been produced in which grains of nitro-starch are held substantially in contact by the use of a colloiding agent, such as nitro-toluene, but as it is well known that colloided nitro-starch is wholly or substantially incapable of detonation, my invention does not contemplate the use of a binding material having such acti -ire tion. Likewise, materials such as oil ha v binding material suitable for my purpose, I may instance commercial glucose. This is a dense adhesive material which does not colloid the nitro-starch particles, has no pronounced desensitizing property, gives the desired consistency to the finished explosive, and furnishes the incompressible fluid ground-mass holding the nitro-starch particles against free movement in the course of the oncoming detonating wave.

In employing the glucose medium for the purpose stated, the proportion of glucose to the other ingredients of the explosive mixture may be varied. Sufiicient glucose should be used, however, to completely fill the voids between the particles of the other constituents of the powder. In other words, the ground-mass should be substantially continuous in the sense that the minute air spaces which surround the individual particles of nitro-starch in ordinary nitrostarch explosives are in large part, if not wholly, displaced by the fluid medium so that each nitro-starch particle, instead of being surrounded by a film of air which prevents the instantaneous rise in temperature necessary to insure the continuance of the detonating wave, is connected to other nitro-starch particles by means of the continuous incompressible medium. With this in view I have obtained satisfactory results with from 5% or 6% to 10% or 12% of glucose. Higher percentages have a tendency to render the mixture sloppy. The ingredients may be thoroughly mlxed in any convenient manner so that the glucose shall be thoroughly incorporated.

Numerous agents having the properties above set forth and capable of use as the ground-mass for the purpose described may be found. I have employed, with success, not only glucose but numerous other agents, such as glycerin, molasses, and paste or jellies made from gelatin, agar-agar or chondrus. The best results are obtained with fluids of high viscosity, having a dense sticky consistency. Taking the viscosity of water as a standard, glycerin has a specific viscosity of approximately 25, and this is the most fluid material which I regard as particularly desirable for my purpose, although any viscosity not less than 10 times that of water might be permissible. In determining viscosity I have used the instrument known as the Scott viscosimeter, with measurements at a temperature of 25 C.

With viscous materials other than glucose the amount of viscous material usable is approximately the same as that above given for glucose, except that, as will be understood, materials of lower viscosity must be used in somewhat smaller amounts than those of higher viscosity, to avoid rendering the mixture sloppy.

A viscous medium with which I have obtained very valuable results, and which may be said to be my preferred agent for the purpose hereinabove described, is a glucose starch jelly made up from 15 parts by weight of starch, 30 parts of glucose and 55 parts of water, this jelly being a very sticky viscous fluid which holds the nitro-starch grains very perfectly together, and serves to transmit the detonating wave with extreme readiness. With nitro-starch explosives containing 50% nitro-starch, inorganic nitrates and the said glucose starch jelly in the proportion of from 6% to 10%, I have made nitrostarch explosives having rates of detonation of 7000 meters per sec- 0nd, and even as high as 7500 meters per second, the explosive thus being far more brisant than either T. N. T. or 60% dynamite. The jelly may contain from 5% to 20% starch, 30% to 60% water, and 10% to 60% glucose, and give satisfactory results.

It will be understood that my invention is applicable to nitro-starch explosives of the various grades, that is to say, containing various proportions of nitro-starch and inorganic nitrates, and it will also be understood that with a nitro-starch explosive of any specific grade, that is to say, having a fixed proportion of nitro-starch, the brisance may be regulated, or varied, within limits by varying the proportion of viscous material employed. My invention can be employed with particularly good results with nitro-starch mixtures containing 30% to 60% nitro-starch and 60% to 30% inorganic nitrates.

I claim:

1. An explosive comprising nitro-starch, an inorganic nitrate, and from 5% to 12% of a viscous fluid free from colloiding action upon nitro-starch.

2. An explosive comprising nitro-starch, an inorganic nitrate, and from 5% to 12% of a non-explosive viscous fluid free from colloiding action upon the nitro-starch.

3. An explosive comprising nitro-starch, an inorganic nitrate and glucose.

4. An explosive comprising nitro-starch, an inorganic nitrate and suflicient glucose to fill the voids among the nitrate and nitrostarch particles- 5. An explosive comprising nitro-starch, an inorganic nitrate and from 5% to 12% glucose.

6. An explosive comprising nitro-starch, an inorganic nitrate and a viscous glucosestarch jelley.

7. An explosive comprising nitro-starch, an inorganic nitrate and sufficient viscous glucose-starch jelly to fill the voids among the nitrate and nitro-starch particles.

8. An explosive comprising nitro-starch, an inorganic nitrate, and from 5% to 12% of a viscous glucose-starch jelly,

9. An explosive comprising an undried mixture of nitro-starch, an inorganic nitrate, and starch paste.

10. An explosive comprising nitro-starch, an inorganic nitrate and glucose-starch jelly, made up from 5% to 20% starch, 30% to 60% Water and 10% to 60% glucose.

11. A nitro-starch explosive comprising 30% to 60% uncolloided nitro-starch, 60%

to 30% inorganic nitrate and 5% to 12% of 10 a fluid having a specific viscosity not less than that of glycerin.

12. An explosive comprising uncolloideol nitro-starch, an inorganic nitrate, and 5% to 12% of a non-explosive fluid having a 15 specific viscosity greater than 10, the viscosity of Water being taken as 1.

JESSE B. BRONSTEIN. 

